Section 18.1 X-rays
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Section 18.1 X-rays • Nature of X-rays • Production of X-rays
© Manhattan Press (H.K.) Ltd.
1
18.1 X-rays (SB p. 4)
Nature of X-rays X-rays — high-frequency electromagnetic waves — λ : 10−8 m - 10−10 m • high penetrating power • weak ionizing power • diffraction in crystals (X-rays are waves) An X-ray film of a broken leg © Manhattan Press (H.K.) Ltd.
Go to
Quiz
2
18.1 X-rays (SB p. 4)
Production of X-rays generated in X-ray tube (2) e- accelerate to anode
(1) heated up to emit e(thermionic emission)
© Manhattan Press (H.K.) Ltd.
(3) e- hit anode, decelerate and emit X-rays 3
18.1 X-rays (SB p. 5)
Production of X-rays large amount energy released at anode Prevent overheating of anode • use metal with high melting point (tungsten) • use copper block behind anode → conduct heat away © Manhattan Press (H.K.) Ltd.
4
To section 18.2
© Manhattan Press (H.K.) Ltd.
5
18.1 X-rays (SB p. 2)
Quiz
1. Which of the following is a nuclear Answe radiation? B. gamma radiation © Manhattan Press (H.K.) Ltd.
r
6
18.1 X-rays (SB p. 2)
Quiz (Cont)
2. Which of the following is not an Answe application of X-rays? r
A. Devices used to check the genuineness of banknotes © Manhattan Press (H.K.) Ltd.
7
18.1 X-rays (SB p. 2)
Quiz (Cont) 3. Can you guess the meaning of “half-life”? A radioactive substance has a half-life of two years. Fill in the blanks. Answe Date
Activity in counts per second
October 1998
3 200
October 2000
1 600
October 2002
800
October 2004
400
October 2008
100
© Manhattan Press (H.K.) Ltd.
r
Return to
Text 8
© Manhattan Press (H.K.) Ltd.
1
18.1 X-rays (SB p. 4)
Nature of X-rays X-rays — high-frequency electromagnetic waves — λ : 10−8 m - 10−10 m • high penetrating power • weak ionizing power • diffraction in crystals (X-rays are waves) An X-ray film of a broken leg © Manhattan Press (H.K.) Ltd.
Go to
Quiz
2
18.1 X-rays (SB p. 4)
Production of X-rays generated in X-ray tube (2) e- accelerate to anode
(1) heated up to emit e(thermionic emission)
© Manhattan Press (H.K.) Ltd.
(3) e- hit anode, decelerate and emit X-rays 3
18.1 X-rays (SB p. 5)
Production of X-rays large amount energy released at anode Prevent overheating of anode • use metal with high melting point (tungsten) • use copper block behind anode → conduct heat away © Manhattan Press (H.K.) Ltd.
4
To section 18.2
© Manhattan Press (H.K.) Ltd.
5
18.1 X-rays (SB p. 2)
Quiz
1. Which of the following is a nuclear Answe radiation? B. gamma radiation © Manhattan Press (H.K.) Ltd.
r
6
18.1 X-rays (SB p. 2)
Quiz (Cont)
2. Which of the following is not an Answe application of X-rays? r
A. Devices used to check the genuineness of banknotes © Manhattan Press (H.K.) Ltd.
7
18.1 X-rays (SB p. 2)
Quiz (Cont) 3. Can you guess the meaning of “half-life”? A radioactive substance has a half-life of two years. Fill in the blanks. Answe Date
Activity in counts per second
October 1998
3 200
October 2000
1 600
October 2002
800
October 2004
400
October 2008
100
© Manhattan Press (H.K.) Ltd.
r
Return to
Text 8
